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AFM Cantilever

An AFM probe is a cantilever, shaped like a tiny diving board with a small, atomic-scale point on the free end. To measure forces at the molecular scale in a liquid, the probe attaches its tip to a molecule such as a protein and pulls; the resulting deflection of the cantilever is measured. The forces are in the realm of piconewtons, or trillionths of a newton. One newton is roughly the weight of a small apple. The new probe design, described in ACS Nano, is the JILA research group's third recent advance in AFM technology.
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Researchers in the Department of Electrical and Computer Engineering at The University of Texas at Austin (UT ECE) have demonstrated the ability to perform nanoscale chemical analysis of molecular films with unprecedented sensitivity by detecting molecular photoexpansion. PhD students Feng Lu and Mingzhou Jin led by Prof. Mikhail Belkin successfully acquired high-quality infrared spectra from as few as 300 molecules in ambient conditions and achieved better than 25 nm spatial resolution. These capabilities enable a highly-sensitive nanoscale analytical tool for chemists, biologists and materials scientists. The results were published in Nature Photonics.more

The Atomic Force Microscope (AFM), which uses a fine-tipped probe to scan surfaces at the atomic scale, will soon be augmented with a chemical sensor. This involves the use of a hollow AFM cantilever, through which a liquid - in this case mercury - is passed under pressure. The droplet of mercury at the tip acts as a sensor. This microscopic fountain pen was developed by researchers at the University of Twente's MESA+ Institute for Nanotechnology. Details of the "fountain pen's" mechanism of action were recently published in Analytical Chemistry.more

Researchers have married two biological imaging technologies, creating a new way to learn how good cells go bad. "Let's say you have a large population of cells," said Corey Neu, an assistant professor in Purdue University's Weldon School of Biomedical Engineering. "Just one of them might metastasize or proliferate, forming a cancerous tumor. We need to understand what it is that gives rise to that one bad cell."more

When an oscillating AFM cantilever approaches a sample, the tip-sample interaction force influences the cantilever dynamics. The magnitude of the contact interaction force depends on the stiffness of the materials. Stiffness of the material affects sensitivity of different modes differently. This sensitivity controls the image contrast. Here, the effect of tip mass on the modal flexural sensitivity of AFM cantilever to the variations of surface stiffness and image contrast is investigated.more

The small size of micro- and nano-structures makes tensile testing challenging. In this study we meet this challenge by combined use of a Focussed Ion Beam (FIB) in Dual Beam configuration, an AFM-cantilever, and a micromanipulator which provide the required accuracy and versatility to measure the mechanical properties of nanowires by tensile testing. AFM cantilevers with a big range of force constants principally enable us to measure the tensile behavior of a great variety of materials.
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